(1) If one wants to express the subordinate subject overtly this can only be if it serves as the subject of a subjunctive clause introduced by the modal complementizer mek [SBJV]. It does not matter if the subordinate subject is coreferential with the main subject or not.
(2) The modal complementizer is a subjunctive marker. Subjunctive mood appears in directive main clauses (e.g. imperatives). It is also present in the subordinate clauses of deontic modality inducing main verbs, i.e. verbs whose meaning contains an element of causation, manipulation, proposal, desire and other affective nuances compatible with deontic modality (e.g. WANT type verbs). Thirdly, subjunctive mood occurs in purpose and consecutive clauses.